/*
  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
  Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad

  Stockfish is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  Stockfish is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef SEARCH_H_INCLUDED
#define SEARCH_H_INCLUDED

#include <atomic>
#include <vector>
#include "misc.h"
#include "move.h"
#include "movepick.h"
#include "types.h"
#include "position.h"
#include "open_book.h"
class Position;

namespace Search {

	/// Stack struct keeps track of the information we need to remember from nodes
	/// shallower and deeper in the tree during the search. Each search thread has
	/// its own array of Stack objects, indexed by the current ply.

	struct Stack {
		Move* pv;
		PieceToHistory* history;
		int ply;
		Move currentMove;
		Move excludedMove;
		Move killers[2];
		Value staticEval;
		int statScore;
		int moveCount;
	};


	/// RootMove struct is used for moves at the root of the tree. For each root move
	/// we store a score and a PV (really a refutation in the case of moves which
	/// fail low). Score is normally set at -VALUE_INFINITE for all non-pv moves.

	struct RootMove {

		explicit RootMove(Move m) : pv(1, m) {}
		bool extract_ponder_from_tt(Position& pos);
		bool operator==(const Move& m) const { return pv[0] == m; }
		bool operator<(const RootMove& m) const { // Sort in descending order
			return m.score != score ? m.score < score
				: m.previousScore < previousScore;
		}

		Value score = -VALUE_INFINITE;
		Value previousScore = -VALUE_INFINITE;
		std::vector<Move> pv;
	};

	typedef std::vector<RootMove> RootMoves;


	/// LimitsType struct stores information sent by GUI about available time to
	/// search the current move, maximum depth/time, if we are in analysis mode or
	/// if we have to ponder while it's our opponent's turn to move.

	struct LimitsType {

		LimitsType() { // Init explicitly due to broken value-initialization of non POD in MSVC
			nodes = time[WHITE] = time[BLACK] = inc[WHITE] = inc[BLACK] =
				npmsec = movestogo = depth = movetime = mate = infinite = ponder = 0;
		}

		bool use_time_management() const {
			return !(mate | movetime | depth | nodes | infinite);
		}

		std::vector<Move> searchmoves;
		int time[COLOR_NB], inc[COLOR_NB], npmsec, movestogo, depth, movetime, mate, infinite, ponder;
		int64_t nodes;
		TimePoint startTime;
	};


	/// SignalsType struct stores atomic flags updated during the search, typically
	/// in an async fashion e.g. to stop the search by the GUI.

	struct SignalsType {
		std::atomic_bool stop, stopOnPonderhit;
	};

	extern SignalsType Signals;
	extern LimitsType Limits;

	void init();
	void clear();
	template<bool Root = true> uint64_t perft(Position& pos, Depth depth);
#ifdef USE_OPENBOOK
	extern bool Is_Have_Book_Move(Position& pos, RootMoves& rootMoves);
#endif

} // namespace Search

#endif // #ifndef SEARCH_H_INCLUDED
